A pick-up truck has a cargo box used to carry various cargos. Generally, the cargo box is covered by a tonneau cover which is releasably clamped to and extended above the cargo box, so as to protect the carried cargos from adverse weather and improve the aesthetic appearance of the pick-up truck. The tonneau covers can be classified into hard-top type and soft-top type, wherein the hard-top type tonneau cover has a hard top made of rigid material, such as metal, fiberglass or the like, while the soft-top type tonneau cover has a soft top made of flexible material, such as canvas, vinyl plastic or a weather-resistant fabric. Moreover, the tonneau cover can be designed to provide a foldable function to help a user to conveniently extend or store the tonneau cover.
Referring now to FIG. 1 and, schematic views of a traditional foldable tonneau cover system of a pick-up truck are illustrated, wherein a tonneau cover system 10 is used to cover a cargo box 21 of a pick-up truck 20, and the tonneau cover system 10 comprises a plurality of frame sections 11, 12, 13, a plurality of hinges 14, a plurality of clamps 15 and at least one cover portions 16. The number of the cover portion 16 can be one or corresponding to that of the frame sections 11-13. The cover portion 16 is made of flexible or rigid material, and can be suitably fixed on the corresponding frame sections 11-13, and can be simultaneously folded when the tonneau cover system 10 is folded. Each of the frame sections 11 is constructed by a plurality of frame members, all of which are made of metal (such as steel, stainless steel, copper, aluminum, equivalent rigid metal or alloy thereof), engineering plastic or even wood. One of the frame sections 11, 13 can be pivotally connected to another adjacent frame section 12 through two or more of the hinges 14, so that all of the frame sections 11-13 can be adjusted to an extended position or a storage position. When the frame sections 11 are in the extended position, the frame sections 11-13 are horizontally extended on two side walls 22 and a tailgate 23 of the cargo box 21, so as to cover an inner space of the cargo box 21. When the frame sections 11-13 are in the storage position, the frame sections 11-13 are folded and stacked on a front end of the two side walls 22, so as to expose the inner space of the cargo box 21.
In the tonneau cover system 10, each of the hinges 14 mainly comprises two pivotal members 141 and a base member 142, wherein each of the pivotal members 141 is installed on frame members of one of the frame sections 11-13, while the base member 142 is pivotally connected between the two pivotal members 141 through two rivet members (not-shown). However, once the base member 142 and the two pivotal members 141 are connected to each other by the rivet members, heads of the rivet members will be deformed to ensure the installation relationship between the base member 142 and the two pivotal members 141. However, after the hinge 14 is long-term used, the base member 142 may be easily damaged, but the base member 142 still can not be detached from the two pivotal members 141 due to the permanent deformation of the heads of the rivet members. As a result, the entire hinge 14 including the two pivotal members 141, the base member 142 and the rivet members must be simultaneously disassembled from the frame members of the frame sections 11-13, so as to complicate the disassembling operation, destroy the original frame construction of the frame sections 11-13 to affect the structural reliability of the frame sections, and increase the maintenance cost of replaced components.
As a result, it is necessary to provide a tonneau cover and a hinge for the foldable tonneau cover to solve the problems existing in the conventional technologies, as described above.